Apex seal having gas pressure bias for a rotary engine

ABSTRACT

A sealing system for a rotary combustion engine according to the present disclosure includes an apex seal fitted in a seal receiving groove in the engine&#39;&#39;s rotor. The groove is arranged at an angle to a plane extending from the rotor&#39;&#39;s center to its apex. The apex seal cooperates with a vane type valve element that directs gas pressure to the area beneath the seal to thereby urge it outwardly. The apex seal has a circumferentially extendlip along the trailing side of its rubbing portion which provides an increased rubbing surface and an increase in the effects of the gas pressure urging the seal outwardly.

1Jnite :1; States atent [191 Batten Mar. 25, 1975 1 AlEX SEAL HAVKNG GAS PRESSURE BIAS FOR A ROTARY ENGINE [21] Appl. No.: 421,470

[51] llnt. Cl F0lc 1.9/02, F040 27/00 [58] Field ofSearch ..418/l13,, 119-124, 418/267, 268

[56] References Cited UNITED STATES PATENTS 72,537 12/1867 Pettit r 418/268 385,805 7/1888 Gregersen ct a1 418/122 2,866,417 12/1958 Nubling 418/122 3,139,072 6/1964 Froede 418/113 3,142,439 7/1964 Froede 418/122 3,176,909 4/1965 Maurhoff 418/123 3,204,615 9/1965 Starmuehler. 3,551,080 12/1970 Feller 418/124 Primary Examiner.1ohn J. Vrablik Attorney, Agent, or Firm-Clifford L. Sadler; Keith L. Zerschling [57] ABSTRACT A sealing system for a rotary combustion engine according to the present disclosure includes an apex seal fitted in a seal receiving groove in the engines rotor. The groove is arranged at an angle to a plane extending from the rotors center to its apex. The apex seal cooperates with a vane type valve element that directs gas pressure to the area beneath the seal to thereby urge it outwardly. The apex seal has a circumferentially extend-lip along the trailing side of its rubbing portion which provides an increased rubbing surface and an increase in the effects of the gas pressure urging the seal outwardly.

4 Claims, 1 Drawing Figure APEX SEAL HAVING GAS PRESSURE BIAS FOR A ROTARY ENGINE BACKGROUND OF THE DISCLOSURE The present invention relates to gas seals for rotary combustion engines, and more particularly to an apex seal for a rotary engine having a trochoid rotor housing and a rotor of generally triangular shape mounted on an eccentric shaft within the housing.

In certain known engines of this type, problems have I BRIEF SUMMARY OF THE DISCLOSURE In the presently preferred embodiment of this invention, an apex seal is provided for a rotary combustion engine of the type having a cavity with a trochoid surface and a generally triangular shape rotor supported in the cavity on an eccentric portion of a shaft.

The seal is of elongated construction and has a generally U-shape in cross section. The apex seal is fitted in a seal receiving groove at one of the apexes of the rotor. The seal receiving groove is arranged at an angle to a radial plane extending through the rotors apex.

The apex seal is interposed between two adjacent pressure chambers within the rotor housing and is angled toward the trailing one of the two chambers.

The sealing system includes a vane type valve situated at the base of the apex seal and communication means for conveying gas pressure from the two adjacent chambers to the valve. The valve is constructed to respond to the greater of the pressures in the two chambers to direct that pressure to the area beneath the apex seal whereby the seal is urged radially outwardly toward the trochoid surface.

A ledge or lip is formed along the trailing side of the seals rubbing surface that engages the trochoid surface. This extension provides an increased rubbing area for the apex seal and, in addition, permits an increase in the effects of gas pressure to urge the seal into engagement with the trochoid surface during certain phases of rotor rotation.

BRIEF DESCRIPTION OF THE DRAWING The many objects and advantages ofa seal system for a rotary combustion engine in accordance with this invention will become apparent upon consideration of the following detailed description and the accompanying drawing, in which the single FIGURE discloses a perspective view of a preferred embodiment of the seal system.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An apex seal for a rotary combustion engine that is constructed in accordance with the presently preferred embodiment of this invention is illustrated in the drawing.

A conventional rotary combustion engine includes a rotor housing having an internal surface that is machined to the shape of an epitrochoid. Housing end walls cooperate with the trochoid surface to provide an internal cavity. A generally triangular shape rotor or rotary piston is eccentrically mounted on a shaft that is rotatably 'supported within the housing. The apexes of the triangular rotor divide the interior of the cavity into three circumferentially spaced apart pressure chambers. The rotor revolves in a planetary fashion about the axis of the shaft and the volume of each chamber is dependent upon the angular position of the rotor in the cavity.

The conventional rotary engine includes a sealing system to ensure the integrity of the three pressure chambers. Such a sealing system provides gas-tight seals between the rotor and the end walls and trochoid surface of the housing. For this purpose, the system includes side seals, corner seals and apex seals all of which are carried by the rotor.

The apex seals are fitted into longitudinally extending seal receiving grooves at the apexes of the rotor and engage the trochoid surface. The corner seals are of generally cylindrical shape and are fitted within cylindrical recesses in the end faces of the rotor at each end of the apex seals. The corner seals are displaceable only axially in their recesses and engage the end walls of the rotor housing. The side seals are of strip form and extend between the corner seals. These seals fit within grooves in the end faces of the rotor.

The present invention is particularly directed to the construction of a unique apex seal system and to the manner in which it cooperates with the rotor and the trochoid surface of the rotor housing.

The apex seal 10 is an elongated member and is formed from a hard material. It fits within a seal receiving groove 12 that is formed at the apex of a rotary piston or rotor 14. The rotor 14 is of triangular configuration and is supported on an eccentric portion of a shaft situated within a housing 16. The rotor 14 is constructed to rotate in the direction of the arrow.

The housing 16 has a trochoid surface 18. A pair of side walls cooperate with the trochoid surface 18 to define a cavity within which the rotor 14 rotates.

The apex seal 10 is constructed to form a gas tight barrier between pressure chambers A and B which are situated on either side of the seal. Chamber B is situated on the leading side of the seal 10 and chamber A is situated on the trailing side.

The groove 12 that receives the seal 10 is arranged at an angle to a plane extending through the center axis of the rotor 14 and the apex where the seal is located. The groove 12 is angled toward the trailing gas chamber A.

The apex seal 10 has a generally U-shape configuration in cross section and includes a pair of legs or side wall portions 20 and 22 that extend inwardly along the sides of the walls of the groove 12. The exposed edge 24 of the seal forms a rubbing surface that engages the trochoid surface 18. An extension 26 is formed along the trailing sides of the rubbing surface 24 whereby the rubbing surface has a broad radius as shown in the drawing.

Means are provided for utilizing gas pressure to urge the seal 10 outwardly into engagement with the trochoid surface 18. A valve assembly 28 includes a vane element 30 that is supported on a pivot pin 32. The pivot pin 32 is located in a semi-cylindrical recess 34 at the base of the seal receiving groove 12.

The vane 30 extends between the sidewalls 20 and 22 of the seal 10 and is constructed to be displaceable into contact with either one or the other of the two sidewalls thereby directing gas pressure to the area beneath the seal 10. For this purpose, a series of passageways are formed in the body of the rotor 14. Passageways 36 provide communication between the surface of the rotor 14 adjacent the gas chamber A and the area at the base of the groove 12 adjacent the valve 28. Similarly, passageways 38 are drilled in the body of the rotor 14 and extend inwardly to provide communication between pressure chamber B and the area at the base of the apex seal 10.

OPERATION The described seal structure operates in the following manner. The rotor 14 will rotate in a planetary fashion within the housing 16 and the gas pressure in the chambers A and B will vary greatly depending upon the phase of the combustion cycle that is occurring in each chamber. The present disclosure includes a means for utilizing gas pressure to urge the seal into engagement with the trochoid surface. Assuming that the gas pressure in the leading chamber B is greater than the gas pressure in the chamber A, such greater pressure will be conveyed to the right side of valve 28 through the passageways 38. The lesser pressure of chamber A will be communicated to the other side of the vane 30. The greater pressure of chamber A will cause the vane 30 to be disposed in the position shown in the drawing. In this position, the edge of the vane 30 is in sealed contact with the sidewall 20 of the apex seal 10. There' fore, the greater pressure in chamber B will be conveyed to the area beneath the seal and the seal 10 will be urged outwardly with its rubbing surface 24 in engagement with the trochoid surface 18.

If, during a different phase of the combustion cycle, the pressure in chamber A exceeds the pressure in chamber B such greater pressure will be communicated through passageways 36 to the left side of the vane 30 as seen in the drawing. The vane 30 will then tilt over until it comes into sealed contact with the apex sidewall 22. Under these circumstances, the greater pressure of chamber A will be conveyed to the area beneath the apex seal 10 whereby the seal will be urged radially outwardly into engagement with the trochoid surface 18.

The valve 28 is of lightweight construction and moves through only a few degrees while being displaced from engagement with the sidewall to sidewall 22 and vice versa. The valve 24, therefore, is very responsive to pressure changes with little lag occurring when there is a change in the pressure differential between the chambers A and B.

Because the seal 10 is angled as described, the sea] does not have a tendency to dig in or bounce along the surface 18 during that phase of the combustion cycle which normally produces chatter marks in a rotary combustion engine. Instead, the sea] surface 24 is wiped along the trochoid surface 18 in a uniform manner.

In one embodiment of the invention, the seal 10 was arranged at an angle of degrees to a plane extending through the center axis of the rotor and the apex of the rotor.

The extension 26 along the trailing edge of the surface ofthe seal 10 permits a rubbing surface 24 that has a broad radius. The rotor 14 is supported on an eccentric shaft and, therefore, the angle between a longitudinal plane of the seal and a tangential plane at the trochoid surface will change during different phases of revolution of the rotor. The abundant breadth of the arcuate rubbing surface 24 will compensate for these changes in contact angle.

The principal means for urging the seal 10 outwardly into engagement with the trochoid surface 18 is the gas pressure in chambers A and B. During engine starting, these pressures may not be entirely adequate and, therefore, spring means such as springs 40 may be provided between the inner edges of the legs or sidewalls 20, 22 and ledges formed adjacent the base of the groove 12. While small coil springs are illustrated in the drawing, leaf springs may be used if desired.

It is intended that the apex seal 10 be used in cooperate with a pair of corner seals as described above. Con ventionally, each corner seal is of generally cylindrical construction and fits within a cylindrical recess in the end face of the rotor.

The foregoing description presents the presently preferred embodiment of this invention. Modifications and alterations may occur to those skilled in the art that will come within the scope and spirit of the following claims.

I claim:

1. A sealing system for a rotary mechanism comprising a housing having a trochoid surface,

a rotor supported for rotation relative to said housing about an orbitting axis parallel to and spaced apart from the axis of said housing,

said rotor having an apex groove defined by a pair of parallel side surfaces,

one of said side surfaces being arranged at an angle to a plane extending through the center axis of said rotor and the outer edge of said one side surface,

an elongated apex seal having a body portion disposed in said apex groove and a rubbing portion engaging said trochoid surface,

said seal being disposed between a leading pressure chamber and a trailing pressure chamber,

said seal being inclined toward said trailing chamber,

said seal having a pair of spaced apart generally fiat sidewalls having exterior surfaces slidably engaging said side surfaces of said groove,

pressure responsive valve means interposed between said spaced apart sidewalls means constructed to convey gas pressure from said leading chamber to one side of said valve means,

means constructed to convey gas pressure from said trailing chamber to the other side of said valve means,

said valve means being constructed to selectively direct gas pressure from that one of said leading chamber and said trailing chamber which has the higher pressure to the area of said seal between said sidewalls whereby said seal is urged outwardly into engagement with said trochoid surface.

2. A sealing system for a rotary mechanism comprising a housing having a trochoid surface,

a rotor supported for rotation relative to said housing about an orbitting axis parallel to and spaced apart from the axis of said housing,

said rotor having an apex groove defined by a pair of parallel side surfaces,

one of said side surfaces being arranged at an angle to a plane extending through the center axis of said rotor and the outer edge of said one side surface,

an elongated apex seal having a body portion disposed in said apex groove and a rubbing portion engaging said trochoid surface,

said seal being disposed between a leading pressure chamber and a trailing pressure chamber,

said seal being inclined toward said trailing chamber,

said seal having a generally U-shape in cross section with a pair of spaced apart generally flat sidewalls,

said flat sidewalls having exterior surfaces slidably engaging said side surfaces of said groove,

pressure responsive valve means interposed between said spaced apart sidewalls,

first means constructed to convey gas pressure from said leading chamber to one side of said valve means,

second means constructed to convey gas pressure from said trailing chamber to the other side of said valve means,

said first and second means being mutually exclusive,

said valve means being constructed to selectively direct gas pressure from that one of said leading chamber and said trailing chamber which has the higher pressure to the area of said seal between said sidewalls whereby said seal is urged outwardly into engagement with said trochoid surface,

said apex seal having a circumferentially extending ledge formed along the trailing side of its rubbing portion whereby said rubbing portion has a width that exceeds the width of said body portion of said apex seal and the distance between said side surfaces.

3. A sealing system for a rotary mechanism according to claim 2 and including:

said first and second means being disposed within said rotor.

4. A sealing system for a rotary mechanism compris ing a housing having a trochoid surface,

a rotor supported for rotation relative to said housing about an orbitting axis parallel to and spaced apart from the axis of said housing,

said rotor having an apex groove defined by a pair of parallel side surfaces,

one of said side surfaces being arranged at an angle to a plane extending through the center axis of said rotor and the outer edge of said one side surface,

an elongated apex seal having a body portion disposed in said apex groove and a rubbing portion engaging said trochoid surface,

said seal being disposed between a leading pressure chamber and a trailing pressure chamber,

said seal being inclined toward said trailing chamber,

said seal having a generally U-shape in cross section with a pair of spaced apart generally flat sidewalls,

said flat sidewalls having exterior surfaces slidably engaging said side surfaces of said groove,

said apex seal being radially displaceable relative to said groove,

pressure responsive valve means interposed between said spaced apart sidewalls,

said spaced apart sidewalls having inwardly facing interior surfaces,

said valve means being sealingly engageable with one or the other of said interior surfaces,

means retaining said valve means against raidal displacement relative to said rotor,

first passage means disposed in said rotor constructed to convey gas pressure from said leading chamber to one side of said valve means,

second passage means disposed in said rotor constructed to convey gas pressure from said trailing chamber to the other side of said valve means,

said first and second passage means being mutually exclusive,

said valve means being constructed to selectively direct gas pressure from that one of said leading chamber and said trailing chamber which has the higher pressure to the area of said seal between said sidewalls whereby said seal is urged outwardly into engagement with said trochoid surface,

said apex seal having a circumferentially extending ledge formed along the trailing side of its rubbing portion whereby said rubbing portion has a width that exceeds the width of said body portion of said apex seal and the distance between said side sur- 

1. A sealing system for a rotary mechanism comprising a housing having a trochoid surface, a rotor supported for rotation relative to said housing about an orbitting axis parallel to and spaced apart from the axis of said housing, said rotor having an apex groove defined by a pair of parallel side surfaces, one of said side surfaces being arranged at an angle to a plane extending through the center axis of said rotor and the outer edge of said one side surface, an elongated apex seal having a body portion disposed in said apex groove and a rubbing portion engaging said trochoid surface, said seal being disposed between a leading pressure chamber and a trailing pressure chamber, said seal being inclined toward said trailing chamber, said seal having a pair of spaced apart generally flat sidewalls having exterior surfaces slidably engaging said side surfaces of said groove, pressure responsive valve means interposed between said spaced apart sidewalls means constructed to convey gas pressure from said leading chamber to one side of said valve means, means constructed to convey gas pressure from said trailing chamber to the other side of said valve means, said valve means being constructed to selectively direct gas pressure from that one of said leading chamber and said trailing chamber which has the higher pressure to the area of said seal between said sidewalls whereby said seal is urged outwardly into engagement with said trochoid surface.
 2. A sealing system for a rotary mechanism comprising a housing having a trochoid surface, a rotor supported for rotation relative to said housing about an orbitting axis parallel to and spaced apart from the axis of said housing, said rotor having an apex groove defined by a pair of parallel side surfaces, one of said side surfaces being arranged at an angle to a plane extending through the center axis of said rotor and the outer edge of said one side surface, an elongated apex seal having a body portion disposed in said apex groove and a rubbing portion engaging said trochoid surface, said seal being disposed between a leading pressure chamber and a trailing pressure chamber, said seal being inclined toward said trailing chamber, said seal having a generally U-shape in cross section with a pair of spaced apart generally flat sidewalls, said flat sidewalls having exterior surfaces slidably engaging said side surfaces of said groove, pressure responsive valve means interposed between said spaced apart sidewalls, first means constructed to convey gas pressure from said leading chamber to one side of said valve means, second means constructed to convey gas pressure from said trailing chamber to the other side of said valve means, said first and second means being mutually exclusive, said valve means being constructed to selectively direct gas pressure from that one of said leading chamber and said trailing chamber which has the higher pressure to the area of said seal between said sidewalls whereby said seal is urged outwardly into engagement with said trochoid surface, said apex seal having a circumferentially extending ledge formed along the trailing side of its rubbing portion whereby said rubbing portion has a width that exceeds the width of said body portion of said apex seal and the distance between said side surfaces.
 3. A sealing system for a rotary mechanism according to claim 2 and including: said first and second means being disposed within said rotor.
 4. A sealing system for a rotary mechanism comprising a housing having a trochoid surface, a rotor supported for rotation relatIve to said housing about an orbitting axis parallel to and spaced apart from the axis of said housing, said rotor having an apex groove defined by a pair of parallel side surfaces, one of said side surfaces being arranged at an angle to a plane extending through the center axis of said rotor and the outer edge of said one side surface, an elongated apex seal having a body portion disposed in said apex groove and a rubbing portion engaging said trochoid surface, said seal being disposed between a leading pressure chamber and a trailing pressure chamber, said seal being inclined toward said trailing chamber, said seal having a generally U-shape in cross section with a pair of spaced apart generally flat sidewalls, said flat sidewalls having exterior surfaces slidably engaging said side surfaces of said groove, said apex seal being radially displaceable relative to said groove, pressure responsive valve means interposed between said spaced apart sidewalls, said spaced apart sidewalls having inwardly facing interior surfaces, said valve means being sealingly engageable with one or the other of said interior surfaces, means retaining said valve means against raidal displacement relative to said rotor, first passage means disposed in said rotor constructed to convey gas pressure from said leading chamber to one side of said valve means, second passage means disposed in said rotor constructed to convey gas pressure from said trailing chamber to the other side of said valve means, said first and second passage means being mutually exclusive, said valve means being constructed to selectively direct gas pressure from that one of said leading chamber and said trailing chamber which has the higher pressure to the area of said seal between said sidewalls whereby said seal is urged outwardly into engagement with said trochoid surface, said apex seal having a circumferentially extending ledge formed along the trailing side of its rubbing portion whereby said rubbing portion has a width that exceeds the width of said body portion of said apex seal and the distance between said side surfaces. 